hi, i'm looking to buy a replacement psu for my father in laws pc. his has two power lead connections in the back, i think one female and one male (if i remember rightly) what is the second connection for? he only uses one. could i replace it with a psu that has one power connection or do i need the two?
Just backing up what Chegs said really, in some older computers (they may be in new ones but I haven't seen them recently) there were two connections; one Male one for the PC which goes into the wall and 1 female one that goes out to the monitor. But if your father-in-law's monitor plugs into a wall socket as well, there is no need for this 'spare' plug and you can replace it with a normal PSU.
Older computers used the main units psu to power the monitor. Your PC has an input for an IEC, from the mains, as all pcs do. The femail connector is an output socket. You would plug the monitor into this. Power would then be controlled by the PC. It was then decided that in the UK all electrical devices should have their own fused plug so this system was deemed noncompliant. Your father in law should power the monitor direcly from the mains. As he does this then a normal 1 socket PSU will be fine.